I’m guessing that if I run the case fans off the Asus chassis headers, there’s no point in using PWM fans. But maybe it’s better to daisy chain everything off CPU header so I can use PWM intake fans?

The Asus Z87 Pro has a CPU_OPT PWM fan header. This header mirrors the CPU PWM header, so it can't be set independently. But it does report the speed of any fan plugged into it. As three pin fan choices the NF-S12A ULN ( 800 rpm top speed) and NF-S12A FLX (1200rpm) are OK, but given that you are dealing with front fan intakes which are more noise-sensitive it might be worth considering the NF-S12A PWM. This fan is supplied with a PWM Y adapter and a PWM extension cable. It would be feasible using the Y adapter and extension cables to run two of these as front intakes from the CPU_OPT header. The advantage of the S12A PWM is the lower speed and reduced noise level at idle and low system stress conditions without the compromise in top speed involved with the S12A ULN. Using the Asus BIOS Silent profile you could expect to see idle speeds of around 350 to 400 rpm and these speeds can be reduced further using Fan Xpert 2 probably to less than 300 rpm. In either case effectively silent. These low PWM fan idle speeds reflect that under low stress conditions Haswell systems need minimal cooling, the CPU will downclock to 800Mhz and undervolt to around 0.7V; a graphics card like the GTX 780 will drop its GPU speed to around 300Mz, also undervolt and even downclock its memory. It is a different matter under the stress of gaming and under these conditions the PWM fans will speed up to give the additional case airflow needed.

given that you are dealing with front fan intakes which are more noise-sensitive it might be worth considering the NF-S12A PWM. This fan is supplied with a PWM Y adapter and a PWM extension cable. It would be feasible using the Y adapter and extension cables to run two of these as front intakes from the CPU_OPT header.

Interesting. I'm looking at the Thermalright HR-02 cooler, which would need just the CPU_FAN header. Does the CPU_OPT header put out enough power to run two PWM fans via a Y-adapter at full speed? I've seen mentions of the Akasa 5-way fan splitter, which has a separate molex connector for power, but wasn't sure if you could run two fans off one header.

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These low PWM fan idle speeds reflect that under low stress conditions Haswell systems need minimal cooling, the CPU will downclock to 800Mhz and undervolt to around 0.7V; a graphics card like the GTX 780 will drop its GPU speed to around 300Mz, also undervolt and even downclock its memory. It is a different matter under the stress of gaming and under these conditions the PWM fans will speed up to give the additional case airflow needed.

That's what I'm aiming at, to have idle and light usage be basically silent with reasonable temps, and not worry too much about the noise when gaming with headphones.

If you want to control all fans independantly then go for 3pins fans and run them from CHA_FAN headers, the Asus Z87 PRO has 3. The choice of fan is your, if you like noctua, the NF-S12A is a fine choice, i would probably go with ULN as its top rpms = 800, and let FanXpert2 control them, i only own the NF-S12A PWM so i cant tell you how low they will drop.

SPCR on the Fan Roundup #6: Scythe, Noiseblocker, Antec, Nexus, Thermalright liked a lot the Noiseblocker NB-Multiframe M12-S1 120mmx25mm Ultra Silent Fan and Scythe Gentle Typhoon AP12, both seems like a good choices for 3pin fans, specially case fans the M12-S1, just is expensive, but compared to Noctua they are very close. It would be easier to mount though, as the rubber inserts come in the fan, so there is no need to use rubber screws, i had a lot of trouble installing my bottom fan as its very hard to get your hand below, this is only with rubber screws, with standard metal is fairly easy as its from the front. Here is the FanXpert2 run on the review, so you get the idea into how low you can take it,

Does the CPU_OPT header put out enough power to run two PWM fans via a Y-adapter at full speed? I've seen mentions of the Akasa 5-way fan splitter, which has a separate molex connector for power, but wasn't sure if you could run two fans off one header.

Yes, I am running two S12A PWM fans off the Z87 Pro CPU_OPT header and it works absolutely OK. For more than two fans I would certainly go with something like the Akasa PWM fan splitter, which distributes the PWM control signal to all of the fans but draws power for the chain separately from the PSU. There is a 3 fan splitter as well as the 5 fan model. Available in the USA from sources such as FrozenCPU.

jdunning wrote:

That's what I'm aiming at, to have idle and light usage be basically silent with reasonable temps, and not worry too much about the noise when gaming with headphones.

If you plug the Antec 3 pin exhaust fan included with the Solo II into one of the Asus chassis fan headers it will give automatic control over around the 7 to 12V range. So again minimal speeds at idle but will automatically run at higher speeds when gaming. With the Z87 Pro motherboard you can set a profile for each chassis fan individually, and slightly better results than the BIOS controls can be achieved by using Fan Xpert 2.

I haven't seen any reports on how well 3pin versions undervolt, but you can be sure that PWM version can go as low as 300RPM. If you have CPU cooler that requires high PWM speeds (some fans need 60-70% to run), you will be forced to run S12A at higher speeds that's necessary.

Compare S12A PWM speeds (left column) with your fan on your CPU heatsink. Right column shows voltage control speeds. If 660RPM is low enough for you anyway (it should be, looking at your system specs), buy PWM version and run it either way it fits you (PWM or voltage). At that speeds all quality fans are inaudible, only airflow "woosh" is present.

About PWM splitters, I don't know about newer boards, but back in LGA775 times, I did set up multiple systems with 3 PWM fans powered only by CPU fan header and I never had any problems. Powering two fans shouldn't be a problem at all, especially since we are talking about slow fans, not requiring much power anyway. If Noctua includes PWM splitter, it should work with no problems.

Edit: I didn't see that you were looking at HR-02. I own this heatsink, it works great as passive heatsink for i7 3770, but included fan (TY-147) has very strange PWM speed curve. It starts spinning at 65% (if I remember correctly) and (like reported in SPCR review) quite poor acoustic footprint (muddy, wooshy, my even has ticking noise). If you will use included fan, you wouldn't want to share CPU fan header with S12A PWM. Mugen 4 would be much better choice, If you are planning using included fan.

Yes, I am running two S12A PWM fans off the Z87 Pro CPU_OPT header and it works absolutely OK.

Thanks, good to know.

What cooler are you using? As axee reminded me below, the performance of the CPU fan affects the case fans, so if it only starts spinning at a fairly high percentage, the case fans will spin faster than needed.

Compare S12A PWM speeds (left column) with your fan on your CPU heatsink. Right column shows voltage control speeds. If 660RPM is low enough for you anyway (it should be, looking at your system specs), buy PWM version and run it either way it fits you (PWM or voltage). At that speeds all quality fans are inaudible, only airflow "woosh" is present.

Thanks for the info. I wasn't sure how PWM fans would behave when voltage controlled, so this helps.

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Edit: I didn't see that you were looking at HR-02. I own this heatsink, it works great as passive heatsink for i7 3770, but included fan (TY-147) has very strange PWM speed curve. It starts spinning at 65% (if I remember correctly) and (like reported in SPCR review) quite poor acoustic footprint (muddy, wooshy, my even has ticking noise). If you will use included fan, you wouldn't want to share CPU fan header with S12A PWM. Mugen 4 would be much better choice, If you are planning using included fan.

I haven't been able to find the Mugen 4 in the States. If it's not available, what would you recommend replacing the stock HR-02 fan with? An NF-A15 PWM? It sounds like replacing the stock fan is a bit tricky as the clips expect a slightly thicker fan than usual.

Abula tried putting A15 on HR-02, afaik there is no problem, since frame is very similar to stock HR-02 fan.

I contacted Noctua about same issuse, they suggested running S12A on heatsink like HR-02:

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I wouldn't recommend to fit a NF-F12-pwm though, because this fan is optimized for heatsinks with tight fin spacing ans usually it is rather noisy when used in low-impedance applications. The NF-A15-pwm is somewhere in between these two fans, but you would have to check whether the additional air flow is required after all.

If you don't plan overclocking, I'm sure that you will be able to run it passively. If it needs just a little bit more cooling, add another S12A on heatsink. A15 could actually be more than you need, same with included TY-147.

Of course Noctua isn't the only option, Scythe Slipstream PWM works great on HR-02, but for case fans I prefer S12A, it's noticable quieter on 500-600RPM (less turbolent noise). Glidestream should be very close. Everything depends on other components, only one HDD is louder than any fan mentioned in this theme below 700 RPM.

As axee reminded me below, the performance of the CPU fan affects the case fans, so if it only starts spinning at a fairly high percentage, the case fans will spin faster than needed.

On my PC i let the CPU fan spin faster than the case fans, for two reasons, it has the most direct impact on the CPU temp, and as you said, and axee this will impact also the speed of the case fans, so i prefer one to run faster vs 4 to run faster, and to me harder to notice rpms on the CPU fan than on case fans that are closer to the outside of the case.

Latest tests with NF-S12A, after 30 minutes prime95, completely stock i7 3770; core temperatures barely reach 70°C. One and only rear fan is spinning between 550-600 RPM. I'm planning on adding fan on HR-02 just for hot summer days, so fans won't spin too fast. On typical workload it usually doesn't even reach 60°C/400RPM, but just in case - it's a music studio workstation and quiet operation is a must all the time!

Link to may "gallery", but it's old. Now, 2.5'' drive is in Quiet drive, and Slipstream is replaced with Noctua:

It's not what I'd accept for myself: validating a fanless system is IMVHO/IME a long and tricky process (even if I think you know better than me).

I'd also note that as adding a couple of 2-400rpm fans to such an heatsink won't be usually audible from inside a good case (not to mention a 5-600rpm exhaust drown out them), there are often no reason to go fanless.

But anyway, eventually, if you're happy with your results, who am I to contraddict them? Cheers.

I'm not sure what is so tricky, temperatures stay at very healthy levels, but if they were to reach any higher, Fan Xpert will kick in with more and more fan speed. PWM fan has plenty of speed left (from 600-1300 RPM) to cool CPU down. So there's no risk on overheating, everything is automatic.

Only "risk" is having fan spinning too fast for my work environment, so I'm planning on adding another fan on HR-02, just to prevent any fan from spinning over 500 RPM at any possible situation!! And I'm talking about NF-S12A, with Slipstreams, the audiable limit is at lower RPM.

Also, we are talking prime95, under usual load over work day temperatures stay under 60°C, fan under 400 RPM, so even adding second fan is really just overblown precaution.

I was surprised also when I was building this PC, I bought 3 Slipstream PWM fans at the time, but after stress testing, I decided to keep just one. There was really just no need for any more. But I agree, in typical PC with multiple fans, 3.5' hard drives and GPU's, there's no reason to go fanless.

It seems to me that the acceptable range of load temperature really depends on each people. I usually get nervous when the load temperature goes beyond 60 Celsius. I recently even underclocked an office rig with i7-2600 from 3.8GHz to 3.0GHz only to make sure the temperature does not rise above 60 Celsius. Given that it is highly likely that the CPU will outlive me, I must say all these obsessions are rather ephemeral.

By the way, one of latest Noctua fans blowing airflow to your huge CPU cooler at 400-600 rpms won't even be audible unless you are capable of perceiving ultrasonic sounds.

I agree, one or two slow fans won't make much of audible difference. But also, why bother? If temperatures are OK... why??

Also about those temperatures: I used to be obsessed about them, but for the last few years, I really don't care much anymore. Even if there is faster degradation, effects will be seen when this CPU will be worth as much as my calculator is right now. There is a safe limit for every component, cooling them more than that is pointless.I't rather use this CPU at it's full potential for a few years that is actually usable, enjoying the silence.

BTW, this discussion about my setup really doesn't belong here, I think author of the topic got the idea of what fan he needs for his particular situation.

Forgot one option!

You can run S12A PWM with LNA and voltage control it. I'm not sure if non-PWM versions are even necessary, this PWM fan undervolts very well. I'm really impressed!

We're pretty off-topic, at any rate to be crystal clear, I specifically commented on the statement "Latest tests with NF-S12A, after 30 minutes prime95, completely stock i7 3770; core temperatures barely reach 70°C". With reference only to that statement, I don't rely just onto Prime95 and 30mins or a few hours of stress-testing, and this is about the half of what I'd not accept for myself.

As a matter of fact, before validating any system of mine, I'm used to test it for stability and overheating using at least Prime95 and FurMark for 24hours continuatively, to which recently I've added a concurrent session of the Anvil's Storage Utilities Endurance Testing, using the logging feature of SpeedFan to log selected temperatures (CPU, GPU but also any motherboard/chipset sensor) data all over that test. Sometime I repeat this procedure logging the fans rotational speeds instead of temperatures.

What's tricky in validating a fanless system? IMO/IME the overall noise signature and the system heat build-up, mostly: and as ggumdol noted, I don't feel comfortable with any CPU temperature which looks like (IMVHO) too much near to the CPU Tcase max, especially a continuously one: and this is about the other half of what I'd not accept for myself.

I am perfectly aware that all and each of the those halves are heavily questionable: nonetheless that's just a concise and frank answer to your question ("Why wouldn't you accept this for yourself?").

Eventually I'd like to stop my off-topic answer with the same closing stating of my previous post: if you're happy with your results, who am I to contraddict them? Cheers.

I'm sorry, but this is pure overthinking. First of all, prime95+furmark is completely unrealistic test. Second of all, those are PWM fans, with my fan curve. If temperature will change, so will fan speed, exponentially. There's no chance of overheating, since at one point, fan will be spinning at full speed!! Third of all, at those temperatures, stock intel cooler would do worst job than my cooling (afterall, it's ivy bridge). And more than 90% of those CPUs are under stock heatsink. Those are perfectly safe temperatures! Plus, all the world review heatsinks after temperature becomes steady. And I have not seen dead CPU for ages.

This is so much overreacting over CPU temperatures, it bizzare. But I think it's the same situation like me explaining why whooshing noise of airflow bothers me and I want total silence. So good conclusion, my friend

BTW, I've updated fans, now I cool actively anyway, just because I can.

This is your personal opinion: I've some educated guess to support what I do, as you have your own personal thoughts about what's realistic or not (in Italy we - trivially - say that: "Opinions are like wearing the horns of a cuckold: at last, everybody sports their own").

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